Subzero: Initial implementation of BB Local CSE

src/IceInst.h

 //===- subzero/src/IceInst.h - High-level instructions ----------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 90 matching lines @@
   bool isDestRedefined() const { return IsDestRedefined; }
   void setDestRedefined() { IsDestRedefined = true; }
 
   Variable *getDest() const { return Dest; }
 
   SizeT getSrcSize() const { return NumSrcs; }
   Operand *getSrc(SizeT I) const {
     assert(I < getSrcSize());
     return Srcs[I];
   }
+  void replaceSource(SizeT Index, Operand *Replacement) {
+    assert(Index < NumSrcs);
+    assert(!isDeleted());
+    assert(LiveRangesEnded == 0);

[Jim Stichnoth, 2016/05/24 04:58:11]

Add a brief comment why this assert is needed (the other asserts are clear).

Something like: Try to ensure this is not called after liveness analysis runs,
because last-use info will surely become incorrect.

[manasijm, 2016/05/24 16:54:21]

Done.

+    Srcs[Index] = Replacement;
+  }
 
   bool isLastUse(const Operand *Src) const;
   void spliceLivenessInfo(Inst *OrigInst, Inst *SpliceAssn);
 
   /// Returns a list of out-edges corresponding to a terminator instruction,
   /// which is the last instruction of the block. The list must not contain
   /// duplicates.
   virtual NodeList getTerminatorEdges() const {
     // All valid terminator instructions override this method. For the default
     // implementation, we assert in case some CfgNode is constructed without a
@@ skipping 1022 matching lines @@
 
 inline Inst *iteratorToInst(InstList::iterator Iter) { return &*Iter; }
 
 inline const Inst *iteratorToInst(InstList::const_iterator Iter) {
   return &*Iter;
 }
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEINST_H